Offense gets shot at somebody else’s ‘D’

The good news for the 49ers‘ quarterbacks: They get to switch from playing against a vaunted defense to the Vikings on Friday night.

Alex Smith, of course, will start the preseason opener against Minnesota and head coach Jim Harbaugh confirmed Monday that Colin Kaepernick, the No. 2 signal-caller entering training camp, will be the first quarterback off the bench. Josh Johnson is listed as No. 3 on the team’s depth chart, with Scott Tolzien as No. 4. Harbaugh said he plans to play each quarterback a “good amount.”

None of the 49ers’ quarterbacks has dazzled in practice recently as a defense that returns all 11 starters has dominated. Harbaugh said the one-sided nature of practices wasn’t a concern. The 49ers ranked second in the NFL in fewest points allowed (14.3 per game) last season.

“The fact that our defense is making our offense better – the fact that there’s 16 other teams that have to look down that gun barrel – makes me the happiest guy in the world,” Harbaugh said.

Baby steps: Wide receiver Michael Crabtree’s latest step in his recovery from a lower-leg injury was a minor one.

For the first time since his injury on the opening day of training camp, Crabtree was on the field in uniform and took part in an individual passing drill. He did not participate in other individual drills and later spent some time running pass routes under the supervision of trainers. He watched the team portion of practice from the sideline.

“He looked good,” Harbaugh said. “I haven’t talked to him yet since practice, but we’ll see how he responds, how he feels tomorrow and what the soreness is like.”

And there were 4: The 49ers are evidently down to four No. 1 wide receivers.

Their depth chart lists Crabtree as one starter. On the other side, Randy Moss “or” Mario Manningham “or” Ted Ginn is listed as the starter.

At the start of training camp, Harbaugh included Kyle Williams as one the five receivers who shared the No. 1 wideout designation. Williams is the No. 2 punt returner behind Ginn.